from greenlet import greenlet
import time


def test1():
    while True:
        print("----A----")
        gr2.switch()
        time.sleep(2) # 效果：延时


def test2():
    while True:
        print("----B----")
        gr1.switch()
        time.sleep(2)


gr1 = greenlet(test1)
gr2 = greenlet(test2)

# 切换到gr1中运行
gr1.switch()
